“Both died without making any confessions”: a finely detailed study of crime and punishment in the days of the Manhattan project.

It was an unlikely pairing: a geeky linguist and codebreaker working for an early iteration of the National Security Agency just after World War II and an earnest FBI agent who teamed up to search out evidence of Soviet espionage inside the atomic bomb program.

At the end of that trail lay the executions of Julius and Ethel Rosenberg and the capture of Klaus Fuchs, but success in breaking up the spy ring and ferreting out the mole deep inside the organization was not without episodes of ineptitude and ball-dropping: “then, without either warning or explanation, two months after the Blue Problem had been launched, it was ended,” writes veteran historian of spookdom Blum (The Last Goodnight: A World War II Story of Espionage, Adventure, and Betrayal, 2016, etc.), a contributing editor at Vanity Fair.

Getting to that mole was one thing; doing so without tipping the Soviets off to the fact that their codes had been broken was quite another. The author’s story, which grows to enfold the Venona program, isn’t entirely new, but it reinforces several points: how thoroughly Soviet agents were able to penetrate the government and scientific circles and the undeniable guilt of those who were eventually brought to justice—and, to boot, the ordinariness of some of the key players (“when Spillane arrived punctually at two, Kalibre, along with his pregnant wife—the woman code-named Wasp—sat with him at the kitchen table”).

Blum is especially good on the motivations that caused some Americans to take the Soviet side. One explained that he felt that the American government committed “gross negligence” in not sharing atomic secrets with its recent ally, while Julius Rosenberg’s haughty arrogance may lose him any sympathy readers might have had before opening the book.

Taut and well-crafted—of great interest to students of spydom and the early Cold War.